A class of sewing machines, generally referred to herein as "pattern tacker" sewing machines, utilize a sewing needle and a movable arch clamp (which moves relative to the head of the sewing machine) for moving a stitchable material relative to a vertically reciprocating sewing needle to sew a particular pattern on the stitchable material. Generally, pattern tackers are capable of sewing multiple patterns and thus allow a user increased versatility. One type of pattern tacker is a programmable sewing machine which includes a computer or equivalent device for storing a variety of sewing patterns which can be accessed and selected by a user. When a particular pattern is selected, the computer controls the movement of the arch clamp (relative to the head of the sewing machine), and hence the stitchable material, relative to the vertically reciprocating sewing needle to generate the selected sewing pattern. More specifically, the computer is interconnected with an arch clamp drive assembly which is capable of providing three-dimensional movement to the arch clamp. Typically, during sewing operations the arch clamp moves along a laterally positioned shaft or rod in the "x" direction or dimension (e.g., perpendicularly to the sewing head), as well as inwardly and outwardly in the "y" direction or dimension (e.g., parallel to the sewing head) via an extendable/retractable shaft or rod positioned perpendicularly to the noted lateral shaft or rod. Depending of course upon the length of the laterally positioned shaft or rod, the arch clamp may have the ability to move laterally outside of the sewing area (e.g., that general area in which sewing operations are performed), for instance to transfer the stitchable material to a material removal assembly as described in U.S. Pat. No. 5,339,756.
A number of devices have been developed to expand the movement of programmable sewing machine pattern tackers in the "x" dimension for sewing larger patterns. For instance, U.S. Pat. No. 5,337,684, issued Aug. 16, 1994 and assigned to the assignee of this patent application, discloses an expansion kit for a programmable sewing machine which effectively alters the time period between which the two extreme limit switches are tripped. These limit switches control the range of movement of the arch clamp in the "x" dimension. Moreover, the assignee of this patent application has manufactured and sold another type of expansion kit for a programmable sewing machine which is illustrated in FIG. 19.
Generally, the expansion kit 800 of FIG. 19 includes a double acting pneumatic cylinder 810 which is mounted on the arch clamp 820 of a programmable sewing machine (e.g., generally similar to the machine 16 of FIG. 1) by a shift clamp housing 830. The cylinder 810 has about a 6-inch stroke via an extendable and retractable rod 860, and the programmable machine for which the expansion kit 800 was designed has the ability to sew a pattern of about 6 inches in the "x" dimension.
The rod 860 of the cylinder 810, which is interconnected with the movable, double acting piston (not shown) therein, is fixedly connected to a shift support block 850. A stabilizing rod 840 extends between the ends of the shift clamp housing 830 for supporting the shift block support 850. A work plate 870 is fixedly attached to the lower portion of the shift block support 850. A pallet clamp (not shown) may be attached to the work plate 870 by the pins 880 and pressure clamps 890. Generally, the pallet clamp retains the material to be sewn and has an opening such that the sewing needle can produce the selected sewing pattern. Consequently, once the material to be sewn is properly positioned within the pallet clamp and such is installed on the work plate 870 in the noted manner, the arch clamp 820 will move in the "x" and "y" dimensions to sew one-half of the sewing pattern on the material with the shift support block 850 being in its first position, for instance, an extreme right position as shown in FIG. 19. Thereafters the piston of the cylinder 810 is shifted to its second position to move the shift support block 850 to its second position, for instance to the left of where it is positioned in FIG. 19, such that the other half of the sewing pattern may be produced in the noted manner. Consequently, the expansion kit 800 allows for patterns to be sewn which are up to twice the size in the "x" dimension of the "x" dimension capabilities of the programmable sewing machine.
Another type of pattern tacker is a cam-driven sewing machine in which the movement of the arch clamp (again relative to the sewing head) is controlled by one or more cams. Typically, the range of movement of the arch clamp in the "x" direction or dimension for a cam-driven pattern tacker sewing machine is limited to the sewing area. Consequently, in order to move the stitchable material outside of the sewing area, for instance to provide the stitchable material to a material removal assembly such as that described in U.S. Pat. No. 5,339,756, other methods such as a manual operator transfers have been previously employed.
Pattern tackers again allow the sewing pattern to be changed to provide increased versatility and utilize an arch clamp. However, other types of cam-driven sewing machines are commercially available, but which are capable of performing only one type of operation (e.g., performing only one type of buttonhole sewing operation) and which do not include a moving arch clamp as described above, For instance, a cam-driven unit, which is available from The Reece Button-Hole Machine Co. of Boston, Mass. and marketed under the name "Reece Rapid Button-Hole Machine", includes a stationary sewing head with a movable table positioned below the sewing head. The table moves the stitchable material relative to the sewing needle which is contained within the sewing head. Unlike pattern tackers which utilize only a vertically reciprocating movement for the sewing needle, the sewing needle in the case of the Reece Rapid Button-Hole Machine utilizes a zig-zag movement (i.e., both vertical and lateral movement). Moreover, the Reece Rapid Button-Hole Machine also includes an integral material removal assembly such that eyelet or buttonhole operations may be performed (i.e., the Reece Rapid Button-Hole Machine provides the requisite material removal operation to define an opening in the stitchable material and sews a pattern to define an eyelet or buttonhole). Typically, an indexer (a separate machine) will be used in combination with the Reece Rapid Button-Hole Machine such that more than one sewing and material removal operation may be performed on a given piece of stitchable material (i.e., the indexer will index/sequentially advance the stitchable material such that, for instance, all of the buttonholes of a shirt may be produced by the combination of the Reece Rapid Button-Hole Machine and the indexer).